package com.doinb.cas;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.atomic.AtomicStampedReference;

/**
 * ABA问题的解决 AtomicStampedReference
 *
 */
public class ABADemo {

    static AtomicReference<Integer> atomicReference = new AtomicReference<>(100);

    // initialRef初始值， initialStamp版本号
    static AtomicStampedReference<Integer> atomicStampedReference = new AtomicStampedReference<>(100, 1);

    public static void main(String[] args) {
        System.out.println("===============ABA问题的产生===============");
            new Thread(()->{
                atomicReference.compareAndSet(100, 101);
                atomicReference.compareAndSet(101, 100);
            },"t1").start();

            new Thread(()->{
                try {
                    TimeUnit.SECONDS.sleep(1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(atomicReference.compareAndSet(100, 2019)+"\t"+atomicReference.get());
            },"t2").start();

        try {
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("===============ABA问题的解决===============");

        new Thread(()->{
            int stamp = atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName()+"\t第一次版本号: "+stamp);
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            atomicStampedReference.compareAndSet(100, 101, atomicStampedReference.getStamp(), atomicStampedReference.getStamp() + 1);
            System.out.println(Thread.currentThread().getName()+"\t第二次版本号: "+atomicStampedReference.getStamp());

            atomicStampedReference.compareAndSet(101, 100, atomicStampedReference.getStamp(), atomicStampedReference.getStamp() + 1);
            System.out.println(Thread.currentThread().getName()+"\t第三次版本号: "+atomicStampedReference.getStamp());
        },"t3").start();

        new Thread(()->{
            int stamp = atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName()+"\t第一次版本号: "+stamp);
            try {
                TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            boolean result = atomicStampedReference.compareAndSet(100, 2019, stamp, stamp + 1);

            System.out.println(Thread.currentThread().getName() + "\t 是否修改成功 result: " + result + "\t当前实际版本号：" + atomicStampedReference.getStamp());

            System.out.println(Thread.currentThread().getName() + "\t当前实际最新值：" + atomicStampedReference.getReference());

        },"t4").start();

    }
}
